function play_start(){
  let playstart = document.getElementsByClassName("playstart");
  // console.log(playstart);
  for(let i=0;i<playstart.length;i++){
    playstart[i].src = "../image/index_img/play_btn2.png";
  }
}
function play_stop(){
  let playstart = document.getElementsByClassName("playstart");
  // console.log(playstart);
  for(let i=0;i<playstart.length;i++){
    playstart[i].src = "../image/index_img/play_btn1.png";
  }
}

function add_start(){
  let addstart = document.getElementsByClassName("addstart");
  // console.log(playstart);
  for(let i=0;i<addstart.length;i++){
    addstart[i].src = "../image/index_img/add_btn2.png";
  }
}
function add_stop(){
  let addstart = document.getElementsByClassName("addstart");
  // console.log(playstart);
  for(let i=0;i<addstart.length;i++){
    addstart[i].src = "../image/index_img/add_btn1.png";
  }
}